ST. LOUIS — Monsanto Co., the world's biggest seed maker, said today its fourth-quarter loss widened to $233 million on lower revenue, led by a drop in sales of its Roundup herbicide, which is facing an onslaught of generic competition.

Its adjusted earnings narrowly beat Wall Street estimates, however.

Monsanto said its loss amounted to 43 cents per share in the quarter that ended Aug. 31. That's larger than its loss of $172 million, or 31 cents per share, a year earlier.

When one-time items are excluded, Monsanto said it earned 2 cents per share on an ongoing basis, beating Wall Street estimates for earnings of 1 cent per share. The estimates typically exclude one-time items.

Revenue fell to $1.88 billion from $2.05 billion the previous year.

The global market for Roundup has been deteriorating as rivals flood the market with generic versions of the chemical.

Sales in the agricultural chemical division, which includes Roundup, fell 12.5 percent to $971 million. By contrast, sales in Monsanto's seed and genomics division fell nearly 4 percent to $908 million during the quarter.

CEO Hugh Grant said Monsanto is still on target to meet its 2007 goal of doubling that year's profits by 2012. The decline in Roundup sales only strengthens Monsanto's plan to focus on genetically engineered crops, while de-emphasizing its longer-standing chemical business.

"We believe today, as we did in the fall of 2007, that the growth of this company is absolutely, directly correlated to the value of our seeds and traits on the farm," Grant said during a conference call Wednesday.

Monsanto is moving ahead aggressively with its plan to release corn plants with multiple engineered genes, called SmartStax corn, during 2010, Grant said. A boost in sales of the more expensive SmartStax seeds helped Monsanto boost its corn seed profits by 10 percent during the fourth quarter.

The company posted a $114 million charge for its restructuring plan that started in the summer and will cut 900 jobs, or 4 percent of its work force. Grant said the job cuts will help Monsanto focus more on selling seeds than chemicals.